2010年4月22日，NIBS周俭民实验室在Cell Host & Microbe杂志发表最新论文。论文报道了一类寄主胞质内受体类似激酶是植物天然免疫信号传导的新的重要元件。
由植物细胞膜受体感受病原相关分子模式激活的免疫反应（PTI）对植物不可或缺。致病微生物常常通过向寄主细胞内分泌一些效应蛋白来抑制PTI信号传导，从而促进病原菌的侵染和增殖。随后植物进化出抗性蛋白特异地识别某些病原菌的效应蛋白再度激活免疫反应（ETI）。携带抗病蛋白RPS5的植物能特异识别丁香假单胞菌的效应蛋白AvrPphB。
AvrPphB是一个半胱氨酸蛋白酶，RPS5在非激活状态时与一个叫PBS1的蛋白激酶形成复合体，后者通过被AvrPphB切割导致RPS5发生构象变化从而变为激活状态。本文发现AvrPphB的原始功能很可能是通过降解与PBS1类似的激酶（PBL）从而抑制PTI来帮助细菌侵染的。研究表明，与PBS1同源的BIK1和PBL1在多条PTI信号通路中起关键作用。它们直接与植物细胞表面受体偶联，激活胞内信号通路。推测PBS1是从PBL家族中演化而来，特异性地识别AvrPphB从而激活ETI。这一发现不仅增进了人们对植物PTI信号传导机理的认识，同时还为ETI的进化方式提供了证据。
NIBS博士后张杰与技术员李魏为本文的共同第一作者，论文的其他作者还有NIBS博士生向婷婷，技术员刘自旭，Purdue University的研究生Kristin Laluk和Tesfaye Mengiste博士, NIBS技术员丁晓军,张晓娟,已毕业博士生邹燕,高明辉,以及陈涉博士和张跃林博士。周俭民博士为本文的通讯作者。此项研究由科技部863和北京市科委资助，在北京生命科学研究所完成。
Michigan State University的Brad Day博士和Sheng Yang He博士在Cell Host & Microbe杂志为该论文配发了题为“Battling immune kinases in plants”的点评，指出该工作为PTI和ETI在进化上相互关联提供了强有力的证据。相关报道见 ｈｔｔｐ://ｗｗｗ.ｃｅｌｌ.ｃｏｍ/ｃｅｌｌ-ｈｏｓｔ-ｍｉｃｒｏｂｅ/ａｂｓｔｒａｃｔ/Ｓ１９３１-３１２８(１０)００１０９-５ 。（生物谷Bioon.com）
生物谷推荐原文出处：
Cell Host & Microbe doi:10.1016/j.chom.2010.03.007
Receptor-like Cytoplasmic Kinases Integrate Signaling from Multiple Plant Immune Receptors and Are Targeted by a Pseudomonas syringae Effector
Jie Zhang1, 4, Wei Li1, 4, Tingting Xiang1, 2, Zixu Liu1, Kristin Laluk3, Xiaojun Ding1, Yan Zou1, Minghui Gao1, Xiaojuan Zhang1, She Chen1, Tesfaye Mengiste3, Yuelin Zhang1 and Jian-Min Zhou1, ,
1 National Institute of Biological Sciences, Beijing 102206, China
2 State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, China
3 Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
Cell-surface-localized plant immune receptors, such as FLS2, detect pathogen-associated molecular patterns (PAMPs) and initiate PAMP-triggered immunity (PTI) through poorly understood signal-transduction pathways. The pathogenic Pseudomonas syringae effector AvrPphB, a cysteine protease, cleaves the Arabidopsis receptor-like cytoplasmic kinase PBS1 to trigger cytoplasmic immune receptor RPS5-specified effector-triggered immunity (ETI). Analyzing the function of AvrPphB in plants lacking RPS5, we find that AvrPphB can inhibit PTI by cleaving additional PBS1-like (PBL) kinases, including BIK1, PBL1, and PBL2. In unstimulated plants, BIK1 and PBL1 interact with FLS2 and are rapidly phosphorylated upon FLS2 activation by its ligand flg22. Genetic and molecular analyses indicate that BIK1, and possibly PBL1, PBL2, and PBS1, integrate immune signaling from multiple immune receptors. Whereas AvrPphB-mediated degradation of one of these kinases, PBS1, is monitored by RPS5 to initiate ETI, this pathogenic effector targets other PBL kinases for PTI inhibition.
